Voltage supply circuit, audio output apparatus, and voltage supplying method

Abstract

A voltage supply circuit is provided. The voltage supply circuit includes a voltage amplifier and a power selecting circuit. A power terminal of the voltage amplifier receives an operation power and outputs a gain voltage for driving an output device. The power selecting circuit receives a plurality of supply voltages and supplies one of the supply voltages to the power terminal of the voltage amplifier as the operation power according to a volume level of an audio signal. An audio output apparatus and a voltage supplying method thereof are also provided. The audio output apparatus includes the voltage supply circuit and a speaker.

Description

CROSS-REFERENCE TO RELATED APPLICATION[0001]This application claims the priority benefit of Taiwan application serial no. 101133541, filed on Sep. 13, 2012. The entirety of the above-mentioned patent application is hereby incorporated by reference herein and made a part of this specification.BACKGROUND OF THE DISCLOSURE[0002]1. Field of the Disclosure[0003]The disclosure generally relates to a voltage supply circuit, and more particularly, to a voltage supply circuit capable of selectively supplying different supply voltages.[0004]2. Description of Related Art[0005]Along with the development of communication and network technologies, telephone devices have been made capable of transmitting audio data (and accordingly making phone calls) through the Internet. When a user makes a phone call by using an IP (Voice over Internet Protocol) phone, the IP phone digitizes and compresses the audio data and then transmits the processed data to a target device through the Internet. The target d...

AI Technical Summary

Benefits of technology

[0018]As described above, a voltage supply circuit selects one of a plurality of supply voltages through a power selecting circuit according to the volume level of an audio signal and supplies the selected supply voltage to a voltage amplifier. The power selecting circuit sets a plurality of volume groups. Herein each volume group is corresponding to a supply voltage. The power selecting circuit supplies an operation power to the voltage amplifier according to the volume group corresponding to the volume level of the audio signal. In addition, the volume detecting circuit converts the volume level of the audio signal into a control signal, and the power selecting circuit supplies the corresponding supply voltage to the power terminal of the voltage amplifier according to the control signal. The operations described above allow the voltage amplifier to dynamically adjust the received supply voltage, so that the power consumption is reduced. Moreover, because the power selecting circuit selects the supply voltage according to the volume level of the audio signal, aforementioned dynamical adjustment won't affect the quality of the audio signal amplified by the voltage amplifier due to insufficient supply voltage.

Problems solved by technology

However, if the external voltage source remains unchanged, unnecessary power consumption may be caused in the IP phone when the volume is changed.

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